Re: Postgres performance slowly gets worse over a month
От | Brian McCane |
---|---|
Тема | Re: Postgres performance slowly gets worse over a month |
Дата | |
Msg-id | 20020811075910.G55427-100000@fw.mccons.net обсуждение исходный текст |
Ответ на | Postgres performance slowly gets worse over a month ("Robert M. Meyer" <rmeyer@installs.com>) |
Список | pgsql-admin |
Robert, I got your email but I am currently at the Mayo clinic with my wife, so I can't give you much help. If you download: ftp://china.maxbaud.net/pub/PostgreSQL/fixtable.pl This is my perl script which will do a live/hot reindex of your tables. You can run the command and it will give you a really short description of options. It should not let you run the script unless yo give it a group of options that actually make sense. I usually run it something like: fixtable.pl -t foo -I bar This will recreate ALL indexes (-I) on table foo (-t foo) in the bar database. I use this thing more often than I would like because I get as much as 1million records changed on a daily basis in one of my tables and the indexes make a big difference in performance (I assume because of disk fragmentation on the large file size). - brian On 8 Aug 2002, Robert M. Meyer wrote: > > Back on July 23, I posted on our performance problem. At that time, I > got several suggestions about what to do to try to fix it. Well, it's > happening again... > > To recap, we have a web based application that utilizes a postgres > backend for handling orders and scheduling. Gradually, the average load > on the system climbs until we dump the database, drop it and reload it > from the dumps. This occurs slowly (weeks, rather than hours) and will > eventually get so bad that no work can get done. Another point is that > the progression of performance appears to be geometric, rather than > linear. I also notice that the size of the data directory starts at > about 4.5 Gig and climbs throughout this process. It's currently at > 6.3Gig. > > We do a full vacuum every night. We have adjusted max_fsm_pages to > 1000000 and max_fsm_relations to 10000 (we were seeing deleted tuples in > the 50K range on some of our tables). We are using ADODB 2.12 in PHP on > Apache 1.3.26 to access the database. We've tried rebuilding all of the > indexes and that didn't help. We're going to try it again because we > wound up corrupting our indexes in the system tables while trying to > drop and recreate a table that got partially created before a system > crash. We suspect that we may have had other problems at the time. We > have a contractor that did the reindex for us so I'm not sure of the > process at this point. I suspect that it's something like; > 1. shut down postgres > 2. run 'postgres -O -P' to start a single user instantiation of the > engine > 3. type 'reindex' to get it to do it > 4. exit postgres and restart the DB with pg_ctl > > Does that sound about right? > > Any other suggestions? We're looking to do something soon before the > load gets out of hand. We have done full DB dumps and restores to fix > this in the past and it takes 4-5 hours in the middle of the night since > we can't take the system down during the day 'cuz we have about 1100 > people sitting on their hands when we do it. One of the suggestions was > to use 'pgmonitor' to keep watch over what's happening but transaction > go through too quickly and nothing seems to tie the system up for any > period of time. We also notice that while the load keeps increasing, > the actual CPU time is very small. We'll see loads above 3 with each > CPU (we have two) sitting with 80%+ idle time. > > As a recap, this is happening on a Compaq Proliant 3500 system with a > five disk raid5 in hardware. > > -- > Robert M. Meyer > Sr. Network Administrator > DigiVision Satellite Services > 14 Lafayette Sq, Ste 410 > Buffalo, NY 14203-1904 > (716)332-1451 > > > ---------------------------(end of broadcast)--------------------------- > TIP 3: if posting/reading through Usenet, please send an appropriate > subscribe-nomail command to majordomo@postgresql.org so that your > message can get through to the mailing list cleanly > Wm. Brian McCane | Life is full of doors that won't open Search http://recall.maxbaud.net/ | when you knock, equally spaced amid those Usenet http://freenews.maxbaud.net/ | that open when you don't want them to. Auction http://www.sellit-here.com/ | - Roger Zelazny "Blood of Amber"
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